In the field of electrical power connectors, US 2011/0237108 A1 is known, which refers to a locking power connector apparatus. A locking panel socket for making an electrical connection with a line plug comprises a socket connection portion having an end lace and the end lace having a plurality of recesses for receiving corresponding power pins of a line plug, a plug insertion channel that extends around the socket connection portion and a panel portion that extends around the plug insertion channel. The locking panel socket also includes within the socket connection portion a locking mechanism for restraining a power pin of a line plug from being withdrawn from one of the recesses and a release mechanism for releasing the locking mechanism to permit the power pin to be withdrawn from the recess. The release mechanism includes an actuation portion and a linking portion that links the actuation portion with the locking mechanism. The actuation portion is manually accessible on the panel and the linking portion extends from the actuation portion to the locking mechanism.
Further, U.S. Pat. No. 7,156,682 B1 discloses an electric socket including a rotation unit and a switching cap unit. The rotation unit abuts the conducting units inside the socket. The switching cap unit protrudes from the rest of the socket. The rotation unit may be moved along with the switching cap unit. When each of the two prongs of a plug is inserted into the two prong slots of the socket, a user may rotate the switching cap unit by a certain angle so that the long sides of the rotation unit may press against the two conducting units of the socket. The two conducting units of the socket seize and lock the two prongs of the plug. To take out the plug, a user may rotate the switching cap unit in the reversed direction by a certain angle, so the two long sides of the rotation unit no longer press against the two conducting units, and the plug may be taken out from the two slots.
In US 2010/0255708 A1, a socket with a plug retention structure is disclosed, which includes an upper housing, a lower housing, at least two flexible pieces, and a control unit. The lower housing includes at least two insertion holes. The interior of the lower housing defines an accommodating space. Two flexible pieces are placed in the accommodating space associated with the lower housing. Each of the two flexible pieces has a fulcrum and at least one flexible plate. One end of the flexible plate is connected to the fulcrum, and the other end of the flexible plate forms an abutting portion. The abutting portions of the two flexible pieces correspond to the two insertion holes. The control unit is movably placed in the accommodating space associated with the upper housing. The control unit is configured to selectively press the flexible plates.
Furthermore, CN 201667452 U relates to a switch socket with a lock catch. The switch socket with the lock catch comprises a shell of the socket and a socket reed arranged in the shell of the socket, and the shell of the socket is provided with a shift lever cam turn plate to guarantee that a plug is firmly contacted with the socket by arranging the lock catch.
U.S. Pat. No. 6,533,598 B1 discloses a lockable wall outlet electrical receptacle having a housing with a pair of vertically spaced electrical plug apertures formed in its front wall surface. An upper and a lower shaft have their front ends extending outwardly from the housing. The shafts have a structure formed in their peripheral surface that allows a predetermined number of degrees of rotation to lock the blade prongs of a male electrical plug in the wall outlet receptacle after they have been inserted into the electrical plug apertures. A mechanical structure having a lever arm for actuation connects the respective upper and lower shaft members so that they are rotated at the same time.
One drawback of the locking and releasing mechanism for restraining the power pin of a plug is, that the mechanism needs a rather voluminous installation space, the connector thus having a size that greatly exceeds that of a standard connector without locking feature, both in the lateral direction and in the insertion direction.